The present invention relates to an electrically actuated door opener assembly, and more particularly, to a positive locking mechanism for overhead garage doors that automatically engages to provide greater security against unauthorized entry through the door in the closed position.
The overhead garage door assembly of the type in wide use typically includes a solid door pivotally mounted in a door frame so that, from the closed position, the door can move pivotally upwardly and rearwardly to an overhead, approximately horizontal position. The assembly also typically includes a remotely controlled mechanism to automatically open and close the door upon command. These automatic garage door openers are of at least four basic types:(1) the frictional engagement form; (2) the rack and pinion form; (3) the chain drive form; and (4) the plastic track drive.
With the frictional engagement form, resilient rollers of the opener frictionally engage a member connected to and extending from the garage door. The force to open and close the garage door is applied by the opener motor to the rollers whose frictional engagement with the extended member causes the door to open and close.
In the rack and pinion type, a rotatable pinion is connected through a guide track to a receiving bracket, which, in turn, is connected to the garage door so that the door may be opened and closed by rotational movement of the pinion.
The chain drive type of automatic garage door opener is exemplified by a commercially available garage door opener manufactured by Genie Home Products, Inc., including models SP-229, SP-129, SP-99 and CH-130. A chain loop is connected to a sprocket on the opener motor at one end of a track, and at the other end of the track the chain is connected to a freely moving sprocket. The chain is also directly connected to the garage door by, for example, an L-shaped bracket so that as the opener motor rotates, the chain rotates with it, moving the L-shaped bracket and thereby moving the door. As an additional feature, the opener motor may rotate in either direction so that the door may be either open or closed upon command.
All types of automatic garage door openers may be subject to unauthorized entry. For example, the frictional type may be forced open by application of sufficient force to the lower portion of the door to overcome the normal frictional bond between the resilient rollers and the extending member, which can create an access opening under the garage door. Using the rack and pinion type as another example, a sufficient force applied to the bottom of the door may cause the receiving bracket to back up along the pinion and thereby also create an access opening under the door. Similarly, the chain drive type of garage door opener is subject to unauthorized entry. For example, the chain may have sufficient "free play" to enable an intruder to slip under a garage door, or the intruder may be able to apply sufficient force to rotate the chain enough to create an access opening under the door.
Regardless of the type of overhead garage door opener, the garage door inherently has some amount of flexibility. The intruder, using this flexibility to his beneift, and possibly in combination with one of the above-described deficiencies of the automatic openers, may be able to pry open a corner and slip through the access opening created thereby.
The overhead garage door assembly and its susceptibility to unauthorized entry is discussed at length and in greater detail in the U.S. Pat. No. 4,254,582 issued to Michael H. McGee. The apparatus described in the McGee patent includes a positive locking mechanism that prevents a person attempting unauthorized entry from forcing reverse movement of the opener. This locking mechanism includes two solenoids secured to the interior of the door frame, two latch members (one for each solenoid) secured on the interior of the garage door. The latch members receive a solenoid plunger when the door is in the closed position and the solenoid is not electrically actuated. Preferably, the solenoid is actuated by a signal from the conventional controls for the garage door opener so that when the opener is electrically actuated, it causes simultaneous actuation of the solenoids to withdraw their plungers from the latch members and release the door for movement from, or movement back, into its closed position. However, the McGee apparatus utilizes a separate power supply which operates independently from the power supply of the garage door opener.
A significant problem with the apparatus described in the McGee patent arises when at least one of the solenoid plungers remains received within its latch member after actuation of opener motor. This condition, wherein the garage door is prevented from movement, may have been caused by one of many reasons, including a failure of the solenoid, a loose electrical connection, or even a mechanical jamming of the plunger within the latch member. In such an instance, the actuated opener motor may continue attempting to open the garage door while the solenoid and latch simultaneously restrain the door in the closed position. This unfavorable situation may result in damage to any of the various components of the garage door assembly, including the expensive possibility of burning the motor windings beyond repair. Alternatively, this situation may result in other types of damage, including the possibility that the solenoid assembly and the associated electrical wires could be torn or pulled from their affixed positions, causing damage to the door and door frame as well as the potential of personal injury from inadvertent contact with a loose or dangling electrical connection, or, at the instant of breakage, from being hit by flying objects such as broken pieces of the splintered door and associated apparatus.